21690616 has 8 divisors (see below), whose sum is σ = 40669920. Its totient is φ = 10845304.

The previous prime is 21690611. The next prime is 21690629. The reversal of 21690616 is 61609612.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21690611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1355656 + ... + 1355671.

It is an arithmetic number, because the mean of its divisors is an integer number (5083740).

Almost surely, 2^21690616 is an apocalyptic number.

It is an amenable number.

21690616 is a deficient number, since it is larger than the sum of its proper divisors (18979304).

21690616 is a wasteful number, since it uses less digits than its factorization.

21690616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2711333 (or 2711329 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 21690616 is about 4657.3185418221. The cubic root of 21690616 is about 278.8842331767.

The spelling of 21690616 in words is "twenty-one million, six hundred ninety thousand, six hundred sixteen".